hi i repair a broken valve, it was broken because bad shims calibration. it was fixed with good seat and the all shims where calibrated on 10, then i put the all the bike togeter and it starts for about 1 minute then the engine just died so i took of spark plugs and i hit the starter buton while i was covering the spark plugs holes with my hand and i feel how every hole suck my hand instead blow my timming is perfect i dont know what happen im so confused any ideas???[][]

 

Umm... That's the force that draws fuel and air into the cylinder. It sucks AND blows, it's called the vacuum effect, it's how syringes work.

 

your shims must be off or your timing. Engine sucks on down stroke through the intake valves while they are open. Then intakes close and exhaust opens on up stroke so it should blow out. My guess timing and shims.